The present application claims the benefit of Japanese Patent Application No. 11-304264 which is hereby incorporated by reference.
1. Field of the Invention
The present invention relates to a microscope, and particularly, to a microscope which is provided with a slider comprising a condenser lens with a ring stop for observing a phase contrast, etc., so as to perform various kinds of observation including a bright field observation and phase contrast observation.
2. Related Background Art
In the field of biological microscopes, in addition to an ordinary bright field observation for observing a specimen by means of an illumination light, various kinds of observation are conducted including phase contrast observation and dark field observation. The xe2x80x9cphase contrast observationxe2x80x9d here means a method of observation by which an illumination light is applied on a translucent specimen of a cell or the like, through a slit so as to visualize the translucent specimen by utilizing the interference between a primary light passing through the specimen and a secondary light diffused by the specimen. The xe2x80x9cdark field observationxe2x80x9d means a method of observation by which a specimen is illuminated in such a manner that the light is not incident directly on an objective lens so as to observe only the light diffused by the specimen.
When the phase contrast observation or the dark field observation is to be conducted, according to a conventional microscope, a slider which is provided with one or a plurality of ring stops for phase contrast observation or for dark field observation is attached to a condenser lens for condensing a light of an illumination lamp to illuminate the specimen, thereby conducting the phase contrast observation or the dark field observation.
When the phase contrast observation or the dark field observation is conduced by attaching the phase contrast observing ring stop or the dark field observing ring stop to the condenser lens, the illumination light is stopped down to an appropriate slit light by means of the phase contrast observing ring stop or the dark field observing ring stop. For this reason, an aperture diaphragm belonging to the condenser lens is required to have an aperture area larger than the outer diameter of the phase contrast observing ring stop or the dark field observing ring stop, so as not to disturb the appropriate slit light which is generated by the phase contrast observing ring stop or the dark field observing ring stop.
Accordingly, in the conventional technology, when the slider provided with the phase contrast observing ring stop or the dark field observing ring stop is attached to the condenser lens, the sides of the slider drive a protrusion for driving the aperture diaphragm of the condenser lens, so that the aperture area of the condenser lens is restricted to be open larger than the outer diameter of the phase contrast observing ring stop or the dark field observing ring stop.
Recently, in the field of biological microscopes, when a biological specimen is to be inspected, there is a strong request for changing over different kinds of observing methods such as the phase contrast observation and the bright field observation, quickly and easily. However, the microscopes meeting such request are limited to the expensive ones provided with turret type condenser lenses, or the like.
On the other hand, as microscopes for students"" practice, comparatively inexpensive ones are employed in which various observing methods are changed over by means of a slider attached thereto. However, there is an increasing tendency that the functions almost the same as those of higher-ranking microscopes are demanded even for the inexpensive ones. Thus such inexpensive microscopes as capable of quickly switching over observing methods are strongly demanded.
However, a conventional microscope of a slider type comprises only means for restricting the aperture diaphragm of the condenser lens to a position open larger than the outer diameter of the phase contrast observing ring stop or the dark field observing ring stop when the slider with the phase contrast observing ring stop or the dark field observing ring stop is attached to the condenser lens,
For this reason, while the slider provided with the phase contrast observing ring stop or the dark field observing ring stop is still attached to the condenser lens, it is impossible to release the restriction of the aperture diaphragm of the condenser lens and to adjust the aperture diaphragm to the numerical aperture of the objective lens.
Accordingly, when the phase contrast observation or the dark field observation and the bright field observation are conducted alternately, it is required to adjust the numerical aperture by extracting the slider from the condenser lens each time the bright field observation is to be conducted. Consequently, a quick changing-over of the observation methods is difficult.
An object of the present invention is to provide a microscope which is capable of quickly changing over observation methods of various kinds, such as the phase contrast observation, the dark field observation, etc.
In order to achieve the above object, the present invention is basically characterized in that a first opening portion and a second opening portion are provided on a slider, and that there is further provided a control means which does not restrict opening/closing of the aperture diaphragm on a side portion of the slider when the second opening portion is disposed on the optical axis of the condenser lens.
According to the present invention, it is possible to quickly change over various kinds of methods of observation with the slider still attached to the condenser lens. Thus, it is possible to adjust the aperture diaphragm of the condenser lens to the numerical aperture of the objective lens when the bright field observation is to be conducted.
In order to achieve the above object, according to the present invention, there is preferably provided a microscope which comprises a condenser lens for condensing an illumination light, a diaphragm disposed on the optical axis of the condenser lens and having a variable aperture area, an aperture setting means for setting the aperture area of the diaphragm, a slider 41 disposed on the light condensing side of the condenser lens and having a first aperture portion having a ring slit and a second aperture portion, a first control means formed, for example, by a first side portion for restricting the aperture area to the full open aperture side when the first aperture portion is disposed on the optical axis of the condenser lens, and a second control means formed, for example, by a second side portion for releasing the restriction on the aperture portion when the second aperture portion is disposed on the optical axis of the condenser lens.
According to the invention described above, since the slider is provided with the first opening portion and the second opening portion, it is possible to make a quick change of between the phase contrast observation using the first opening portion and the bright field observation using the second opening portion, while the slider 41 is still attached to the condenser lens. When the bright field observation using the second opening portion is to be conducted, since the microscope has the second side portion for releasing the restriction on the aperture area of the diaphragm, it is also possible to adjust the aperture diaphragm of the condenser lens to the numeral aperture of the objective lens.